L'essentiel en 10 secondes
DPI and PPI are the same
They both measure pixel density.
Resolution defines real size
Same pixels, different DPI = different physical size.
3 key values
72 (web), 150 (large print), 300 (print).
Changing DPI doesn’t improve quality
It only adds fake pixels.
Always calculate before designing
Avoid export issues and errors.
Why DPI and PPI are confusing
You work on a screen in pixels. Your printer asks for centimeters and DPI. Between the two, things get blurry. And if you get it wrong, your image will either look pixelated or generate a massive unusable file.
DPI (Dots Per Inch) and PPI (Pixels Per Inch) refer to the same concept: pixel density over a physical distance. It’s the missing link between your screen and print.
Without understanding this, you end up guessing, making mistakes, and redoing your work. With the right method, you get it right in seconds.
The real problem: three different worlds
When creating images for print, you deal with three systems:
- Screen: pixels (1920 × 1080 px)
- Print: physical size (e.g. 21 × 29.7 cm for A4)
- Resolution: determines quality (72 DPI for web, 300 DPI for print)
The key mistake: pixels alone are meaningless for print. Resolution defines real-world size.
Example: a 1920 × 1080 image at 72 DPI equals 67.7 × 38.1 cm. At 300 DPI, it becomes 16.3 × 9.1 cm. Huge difference.
How DPI conversion works
Formula:
Dimension (cm) = (Pixels ÷ DPI) × 2.54
Why 2.54? Because 1 inch = 2.54 cm.
Reverse formula:
Pixels = (cm ÷ 2.54) × DPI
Example: A5 flyer (14.8 × 21 cm) at 300 DPI:
→ 1748 × 2480 pixels
Always define resolution before starting.
The 3 key resolutions
72 DPI → web and screens
150 DPI → large formats viewed from a distance
300 DPI → standard for print (flyers, magazines, business cards)
Warning: increasing DPI on an existing image does NOT improve quality. It only adds fake pixels.
Example: preparing a print file
A4 flyer (21 × 29.7 cm) at 300 DPI:
→ 2480 × 3508 pixels
Create your document with these dimensions before designing.
Save time with a tool
Manual calculation works, but is error-prone.
With a tool, you input values and get instant results in pixels, cm, and inches.
You can also upload an image to check if it’s suitable for print.
Key takeaway
DPI conversion is simple once you understand pixel density.
Remember:
- 72 DPI for web
- 150 DPI for large prints
- 300 DPI for high-quality print
Define resolution first, then calculate your dimensions.
DPI / PPI Converter
Convert your dimensions in pixels, centimeters or inches based on the resolution (DPI). Ideal for preparing files for print or web.
Sources & Méthodologie
- Adobe documentation on image resolution
- Print industry guidelines (Antalis)
- Outilo methodology based on standard DPI formulas
Contenu validé par Yoann Begue, Creator & developer of Outilo — practical tools for everyday use.
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